The present invention relates to a photokeratometric device for attachment to a photoslit lamp microscope and, more particularly, to a photokeratometric device mounted on a photoslit lamp microscope for measuring the curvature radius, shape and optical characteristics of the cornea of an eye under examination.
A photokeratometer has been disclosed in the prior art in which a coaxial annular pattern, referred to as a Placido pattern, is projected on the cornea of an eye under examination and a photograph of an image reflecting from the cornea is taken. The photograph is photodensitometrically measured to obtain data, e.g., the curvature radius, shape and optical characteristics of the cornea. Since a photokeratometer is normally an independent ophthalmic instrument, it cannot readily be mounted on a photoslit lamp microscope.
A hand held Placido pattern disc also has been known in the ophthalmic field. This Placido pattern disc includes a plurality of LEDs (light emitting diodes) arranged thereon to project a Placido pattern on the cornea. An image reflected from the cornea is observed through an ophthalmoscope.
In photographing the cornea image, however, it has been difficult to properly position a Placido disc and therefore it has not been possible previously to use a Placido disc in photokeratometry.